1. Field of the Invention
The present invention relates to a packaging process of a light emitting diode (LED), and more particularly to a packaging process of an LED capable of increasing the viscosity of an encapsulant of an LED package rapidly.
2. Description of Related Art
Due to the advantages of long lifetime, compactness, high vibration resistance, low heat emission, and low power consumption, light emitting diodes (LEDs) have been widely applied in indicators or light sources of various home appliances and instruments. With recent development towards multicolor and high illumination, the applications of the LEDs are extended to large-sized outdoor billboards, traffic lights, and the like. In the future, the LEDs may become the power-saving and environment-friendly light sources in replacement of tungsten filament lamps and mercury vapor lamps.
Generally, an LED package includes a carrier, an LED chip, and an encapsulant. The LED chip is disposed on the carrier and electrically connected to the same. The encapsulant encapsulates the LED chip and a portion of the carrier to protect the LED chip and expose a portion of the carrier outside of the encapsulant to provide a function of external electrodes. Since light emitted by the LED chip is transmitted to the outside of the LED package through the encapsulant, the encapsulant of the LED not only has a function of protecting the LED chip, but is also closely related to overall light emitting efficiency and optical characteristic of the LED.
In the conventional packaging process of the LED, the manufacture of the encapsulant is generally categorized into compression molding and transfer molding. In the process of compression molding, a substrate having LED chips mounted thereon is inserted into a mold which contains a melted encapsulant, after the encapsulant has been cured, an entire package is released from the mold to complete the encapsulating process. In the process of transfer molding, a substrate having LED chips mounted thereon is clamped by a mold, and a melted encapsulant is injected into the molding cavity of the mold to encapsulate the LED chip, after the encapsulant has been cured, an entire package is released from the mold to complete the encapsulating process.
However, both the compression molding and the transfer molding require molds and expensive injection machines, which results in a certain manufacturing cost. Moreover, a molding cavity of the mold may be deformed or damaged after being used for a period of time, thereby changing a configuration of the encapsulant formed and further affecting yield rate. In addition, since the making and modifying of the molds both require repetitive developments and adjustments, the molds can not be developed and modified quickly according to different designs. As a result, the production time is likely to be delayed. Hence, how to improve the packaging process is one of the issues that have to be conquered in the manufacture of the LED.